Integrated blood handling system having active gas removal system and methods of use

ABSTRACT

Apparatus and methods for pumping and oxygenating blood are provided that include a gas removal system. An integrated blood processing unit is provided in which a gas removal/blood filter, pump and blood oxygenation element are mounted within a common housing. The gas removal system includes a sensor mounted on the housing to sense the presence of gas, and a valve is operably coupled to the sensor to evacuate gas from the system when the sensor detects an accumulation of gas.

FIELD OF THE INVENTION

[0001] The present invention relates to apparatus and methods forpumping, oxygenating and filtering blood having means for removing airor other gasses from the blood.

BACKGROUND OF THE INVENTION

[0002] Each year hundreds of thousands of people are afflicted withvascular diseases, such as arteriosclerosis, that result in cardiacischemia. For more than thirty years, such disease, especially of thecoronary arteries, has been treated using open surgical procedures, suchas coronary artery bypass grafting. During such bypass graftingprocedures, a sternotomy is performed to gain access to the pericardialsac, the patient is put on cardiopulmonary bypass, and the heart isstopped using a cardioplegia solution.

[0003] The development of minimally invasive techniques for cardiacbypass grafting, for example, by Heartport, Inc., Redwood City, Calif.,and CardioThoracic Systems, Inc., Menlo Park, Calif., have placed apremium on reducing the size of equipment employed in the sterile field.Whereas open surgical techniques typically provide a relatively largesurgical site that the surgeon views directly, minimally invasivetechniques require the placement of endoscopes, video monitors, andvarious positioning systems for the instruments. These devices crowd thesterile field and can limit the surgeon's ability to maneuver.

[0004] At the same time, however, the need to reduce priming volume ofthe oxygenator and pump, and the desire to reduce blood contact withnon-native surfaces has increased interest in locating the oxygenatorand pump as near as possible to the patient.

[0005] In recognition of the foregoing issues, some previously knowncardiopulmonary systems have attempted to miniaturize and integratecertain components of cardiopulmonary systems. U.S. Pat. Nos. 5,266,265and 5,270,005, both to Raible, describe an extracorporeal bloodoxygenation system having an integrated blood reservoir, an oxygenatorformed from a static array of hollow fibers, a heat exchanger, a pumpand a pump motor that is controlled by cable connected to a controlconsole.

[0006] One drawback of systems of the type described in foregoingpatents, however, arises during priming of the extracorporeal circuit,and in particular, in the need to use large quantities of saline ordonor blood to prime the systems. Such fluids are required to flush airout of the system and, because they are relatively incompressible,ensure that the pump used in the extracorporeal circuit developssufficient pressure head to propel oxygenated blood back to the patient.

[0007] In view of this limitation of previously known blood handlingsystems, it would be desirable to provide a blood handling system andmethods that automatically remove air from an extracorporeal bloodcircuit.

[0008] It further would be desirable to blood handling systems andmethods that permit one or more additional blood processing components,such as a heat exchanger, to be added to an extracorporeal blood circuitwithout having to prime the component prior to bringing that componentonline, thereby reducing disruption to operation of the blood handlingsystem.

[0009] It also would be desirable to provide an extracorporeal bloodhandling system and methods wherein the blood handling system hascompact size and low surface area, and reduces contact between the bloodand foreign surfaces, thus reducing priming volume, hemolysis andplatelet activation.

[0010] It still further would be desirable to provide a blood handlingsystem and methods that provide progressive filtration of blood passingthrough the system, thus reducing the risk that a single blood filterelement will become clogged during extended operation.

SUMMARY OF THE INVENTION

[0011] In view of the foregoing, it is an object of the presentinvention to provide apparatus and methods for handling blood thatautomatically remove air from an extracorporeal blood circuit.

[0012] It is another object of the present invention to provide a bloodhandling system and methods that permit one or more blood processingcomponents, such as a heat exchanger, to be added to an extracorporealblood circuit without having to prime the component prior to bringingthat component online, thereby reducing disruption to operation of theblood handling system.

[0013] It is yet another object of this invention to provide anextracorporeal blood handling system and methods wherein the bloodhandling system has compact size and low surface area, and reducescontact between the blood and foreign surfaces, thus reducing primingvolume, hemolysis and platelet activation.

[0014] It is a further object of the present invention to provide ablood handling system and methods that provide progressive filtration ofblood passing through the system, thus reducing the risk that a singleblood filter element will become clogged during extended operation.

[0015] These and other objects of the present invention are accomplishedby providing a blood handling system comprising an integrated bloodoxygenator and pump system having means for removing air or other gasesfrom the extracorporeal blood circuit. In accordance with the principlesof the present invention, the blood handling system includes a gascollection plenum, a line adapted to be connected to a suction source,and a sensor that controls coupling of the suction source to the gascollection plenum to selectively remove gas from the blood handlingsystem. The blood handling system of the present invention therefore maybe initially primed with little or no saline or donor blood, and withreduced risk of hemodilution.

[0016] Moreover, additional components may be added to an existingextracorporeal circuit with little or no additional priming, and any airor other gases introduced into the system will be evacuated with nosubstantial impact on operation of the blood pump of the blood handlingsystem.

[0017] In a preferred embodiment, a blood handling system of the presentinvention maintains total or partial bypass support for a patient andcomprises a housing having a blood inlet, a blood outlet, a gascollection plenum, a blood oxygenation element, a blood pump and a gasremoval system.

[0018] Blood entering the housing via the blood inlet flows through thegas collection plenum and a first blood filter component that forms partof the gas removal system. Air or other gases entrained in the blood areseparated from the blood and collect in the gas collection plenum. Asensor disposed in communication with the gas collection plenum senses aparameter indicative of a level or volume of gas collected in theplenum, and selectively evacuates the plenum by coupling the plenum to asuction source, such as a standard operating room suction port.

[0019] Blood exiting the first blood filter component passes to acentrifugal blood pump, which propels the blood through the bloodoxygenation element. The blood oxygenation element preferably comprisesan annular fiber bundle, e.g., an annular bundle of hollow gas exchangetubes, positioned within the housing. In accordance with another aspectof the present invention, the annular filter bundle serves as a secondblood filtration element.

[0020] Blood exiting the blood oxygenation element then passes throughan additional blood filter element before exiting from the housingthrough the blood outlet. Blood processed through the system thereforepasses through multiple blood filters, which may be progressively finer,distributed throughout the housing, thereby reducing the risk that anyone of the filters will be overburdened and clog during extended use ofthe system.

[0021] In still another aspect of the invention, the blood oxygenationelement receives blood from the blood pump on a side of the annularfiber bundle that is diametrically opposite to the blood outlet. Theinlet to the annular fiber bundle preferably includes an inlet manifoldand the blood outlet of the housing preferably has an outlet manifold.The inlet and outlet manifolds preferably extend longitudinally alongdiametrically opposite sides of the blood oxygenation element, so thatblood flows from one side to the diametrically opposite side of theblood oxygenation element.

[0022] In a preferred embodiment, the gas removal system includes a gasremoval/blood filter element having a cylindrical shape. The gasremoval/blood filter comprises a support structure that supports ascreen-like material having an effective pore size between 40 and 250microns. Alternatively, the gas removal/blood filter element maycomprise a pleated filter material. Blood is introduced into the gascollection plenum via the blood inlet in a direction substantiallytangential to the gas removal/blood filter, to increase residence timeof the blood within the gas collection plenum, thereby enhancingseparation of entrained gas.

[0023] In still another aspect of the present invention, the housing ofblood oxygenation element includes at least one relief area positionedradially inward from the annular fiber bundle. More preferably, a reliefarea is positioned radially inward from each of the inlet and outletmanifolds to permit expansion of the annular fiber bundle at theselocations, and to increase the porosity of the fibers in the manifoldarea and decrease resistance to flow.

[0024] Methods of operating the blood handling system of the presentinvention also are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects and advantages of the presentinvention will be apparent upon consideration of the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout, and inwhich:

[0026]FIG. 1 is a schematic depiction of an extracorporeal blood circuitusing the blood handling system of the present invention;

[0027]FIGS. 2A and 2B are, respectively, perspective and explodedperspective views of the integrated blood-processing component of thepresent invention;

[0028]FIG. 3 is a side-sectional view of the integrated blood processingcomponent of the present invention;

[0029]FIG. 4 is a cross-sectional view of apparatus similar to that ofFIG. 3, taken along line 4-4 in FIG. 3, depicting the use of reliefareas adjacent to the inlet and outlet manifolds;

[0030]FIGS. 5A and 5B are, respectively, perspective and cross-sectionalviews of a gas removal/blood filter element of the gas removal system ofthe present invention;

[0031]FIGS. 6A and 6B are, respectively, perspective and cross-sectionalviews of an alternative gas removal/blood filter element of the gasremoval system of the present invention;

[0032]FIG. 7 is a cross-sectional view of a gas removal/blood filter ofthe gas removal system of the present invention configured for use inpreviously known extracorporeal blood processing systems;

[0033]FIG. 8 is a side-sectional view of alternative embodiment of theintegrated blood processing component of the present invention;

[0034]FIGS. 9A and 9B are, respectively, exploded perspective and sideviews of the impeller, bearing assembly and shaft of the blood pump ofthe present invention;

[0035]FIG. 10 is an exploded perspective view depicting an injectionmolding process for the impeller of FIGS. 9;

[0036]FIGS. 11A and 11B are front and rear perspective views of theblood handling system of the present invention; and

[0037]FIGS. 12A and 12B are representative screens depicting the displayof parameters monitored and/or controlled by the blood processing systemof the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0038] Referring to FIG. 1, extracorporeal blood circuit 10 includingblood handling system 30 of the present invention is described.Extracorporeal blood circuit 10 is designed for maintaining a patient onfull or partial bypass support, for example, during a coronary arterybypass graft procedure or mitral valve repair procedure.

[0039] Extracorporeal blood circuit 10 includes venous line 11 thatcarries deoxygenated blood from patient P to blood handling system 30,and arterial line 12 that returns oxygenated blood to the patient. Eachof venous line 11 and arterial line 12 are coupled to the patientthrough a suitable cannula, which is per se known. In accordance withknown methods, the venous and arterial cannulae may be positioned in anysuitable vein or artery.

[0040] Venous line 11 is coupled to inlet line 13 of blood handlingsystem 30 via lines 14, 15 and 16. Line 14 preferably includes dynamicreservoir 17 that can be selectively added and removed from the circuitusing valves 18 and 19. Dynamic reservoir 17, which preferably is aflexible storage bag, permits blood to be stored or supplied to bloodhandling system 30 as necessary. Valves 18 and 19 control blood flowinto and out of dynamic reservoir 17. One advantage of this arrangementof extracorporeal blood circuit 10 is that the pump of the bloodprocessing component may be used to fill and evacuate the dynamicreservoir 17 during operation by simply manipulating valves 18 and 19.Alternatively, a conventional venous storage reservoir may be usedinstead of dynamic reservoir 17.

[0041] Line 15 includes valve 20 which may be activated to direct bloodcoming from the patient to either or both of lines 13 and 16. Line 16,which may include additional valving (not shown) permits additionalblood processing unit 21, such as an additional filter or heatexchanger, to be included in extracorporeal blood circuit 10. Optionalrecirculation line 22 includes valve 23, and permits a portion of theoutput of blood handling system 30 to be recirculated to the input ofthe blood handling system, or used in administration of cardioplegia tothe patient.

[0042] Blood handling system 30 includes integrated blood processingcomponent 31 coupled to drive unit 32 and controller 33. In accordancewith one aspect of the present invention, blood handling system 30 has agas removal system including sensor 37 and valve 36 adapted to becoupled to suction source 34 via line 35. Valve 36 and sensor 37preferably are electrically coupled to controller 33 so that controller33 can regulate operation of valve 36 responsive to an output of sensor37. As explained in greater detail hereinafter, the gas removal systemof the present invention removes air and other gases from extracorporealblood circuit 10 and blood processing component 21 during priming andoperation of the bypass system.

[0043] Referring now to FIGS. 2A, 2B and 3, integrated blood precessingcomponent 31 combines the features of previously known bloodoxygenators, blood pumps, and blood filters into a single housing. Inaccordance with one aspect of the present invention, the blood handlingsystem also provides for continuous monitoring and removal of air orother gases from the extracorporeal blood circuit during priming andoperation.

[0044] Blood processing component 31 includes housing 40 having bloodinlet 41, blood outlet 42, recirculation outlet 43, gas inlet port 44,gas outlet port 45 and gas removal port 46. Blood outlet 42 andrecirculation outlet 43 are disposed from blood outlet manifold 47,which is disposed diametrically opposite blood inlet manifold 48 ofhousing 40. Blood processing component 31 preferably includes tabs 49 orother means for coupling blood processing component 31 to reusable driveunit 32.

[0045] Illustratively, housing 40 comprises a series of parts that eachdefine a compartment: gas collection plenum 50, central void 51, uppergas plenum 52, annular fiber bundle compartment 53, lower gas plenum 54and pump space 55. In a preferred embodiment, central void includes alarger diameter upper portion and a smaller diameter lower portion. Aswill of course be understand, the parts shown in exploded view in FIG.2B could be molded or cast in more or fewer pieces.

[0046] Gas collection plenum 50 encloses a gas removal/blood filter 56that extends within upper portion of central void 51. Gas removal/bloodfilter 56 causes gas entrained in blood introduced into the gascollection plenum to separate and collect in the upper portions of gascollection plenum 50. Gas removal/blood filter 56 comprises generallyconical upper wall 57, baffled support structure 58 and filter material59. Blood inlet 41 is displaced tangentially relative to the centerlineof housing 40, so that blood passing through blood inlet 41 into gascollection plenum 50 swirls around upper wall 57, which is preferablyfluid impermeable.

[0047] Upper wall 57 also preferably includes a chamber having a centralopening through its upper surface, which communicates with the upperportion of gas collection plenum 50. This configuration allows any gasthat passes through filter material 59 to escape through the opening inupper wall 57 and be evacuated from gas collection plenum 50.Advantageously, this feature facilitates rapid and easy priming of bloodprocessing component 31, as described hereinbelow.

[0048] Filter material 59 comprises one or multiple layers of ascreen-like material having an effective pore size of between 40 and 250microns, and is mounted to baffled support structure 58. Filter material59 serves to exclude bubbles from the blood flow by maintaining theswirling action of the blood in the central void for a sufficient timeto allow the bubbles to rise to the gas collection plenum. Because theblood circulates around the outside of gas removal/blood filter 56 incentral void 51, bubbles impinge against filter material 59tangentially, and thus “bounce off.” Filter material 59 preferably alsoforms a first stage of a progressive blood filter that is distributedthroughout the blood processing component, and filters out relativelylarge particulate matter.

[0049] As illustrated in FIGS. 5A and 5B, support structure 58 forms anopen cage 60 having longitudinal struts 61 and support rings 62. Struts61 extend radially inward and preferably include radiused inner ends 63.Struts 61 serve as baffles to reduce swirling of blood that has passedthrough filter material 59. In an alternative embodiment, shown in FIGS.6A and 6B, struts 61 are further extended radially inward to form fluidimpermeable cruciform structure 63.

[0050] Referring again to FIG. 3, blood oxygenation element 70 isdisposed within annular fiber bundle compartment 53, and comprises amultiplicity of gas permeable fibers arranged in an annular bundle. Asis well known in the art, the gas permeable fibers are potted near theupper and lower ends of the bundle so gas may pass through the interiorof the fibers via the ends of the fibers, while allowing blood to passalong the exteriors of the multiplicity of tubes in the bundle. Thebundle therefore includes upper potting region 71 that separates theblood flow region within the annular bundle from upper gas plenum 52,and lower potting region 72 that separates blood flow region from thelower gas plenum 54.

[0051] Blood passing into the annular fiber bundle compartment 53 fromblood inlet manifold 48 therefore flows through blood oxygenationelement 70 and to blood outlet manifold 47. In accordance with oneaspect of this invention, the annular fiber bundle also provides somefiltration of blood passing through blood processing component 31, byfiltering out particulate matter that has passed through filter material59 employed in gas removal/blood filter 56.

[0052] The lower portion of central void 51 communicates with pump space55, in which centrifugal impeller 75 is disposed. Impeller 75 includes aplurality of vanes 76 and is mounted on shaft 77 via bearings 78.Impeller 75 preferably comprises an injection-molded part that enclosesa ferromagnetic disk, so that the disk may be magnetically coupled todrive unit 32 (see FIG. 1). Blood accelerated by impeller 75 is ejectedfrom pump space 55 via a passageway that includes curved ramp 79. Ramp79 serves to redirect radially outward blood flow from impeller to alongitudinal flow within blood inlet manifold 48.

[0053] In a preferred embodiment, oxygen is introduced into upper gasplenum 52 through gas inlet port 44, passes through the interiors of themultiplicity of hollow fibers in blood oxygenation element 70. Carbondioxide, any residual oxygen, and any other gases exchanged throughblood oxygenation element 70 exit into lower gas plenum 54, and areexhausted through gas outlet port 45.

[0054] In accordance with the present invention, blood processingcomponent 31 also includes sensor 37 that monitors the level of gas orblood in gas collection plenum 50. Sensor 37 may sense a parameterindicative of a level or volume of air or other gas in gas collectionplenum 50, or may simply detect the absence of blood, and may be anysuitable sensor that preferably operates by a non-contact method.Suitable sensor methods include electrical-charge based, optical andacoustic methods. A resistive contact method also could be employed, inwhich a low electrical current is passed between adjacent electrodesonly in the presence of blood.

[0055] Sensor 37 preferably is of a capacitance type, per se known inthe art, that detects a change in electrical capacitance between thebulk of a liquid (in this case, blood or saline) and gas. Alternatively,sensor 37 may be optical in nature, and use a light source that has awavelength that is minimally attenuated by blood. In this case, thelight source is directed, at an oblique angle, through the blood at thetop of the gas collection plenum towards a photodetector, and the sensoris positioned to detect the change in the refractive index of the blood(or saline prime) caused by the presence of air or other gases. Inanother alternative embodiment, sensor 37 may use an ultrasonic energysource and receiver to detect the presence of gas or absence of blood bythe change in acoustic transmission characteristics.

[0056] The output of sensor 37 is supplied to controller 33 of bloodhandling system 30 (see FIG. 1) which in turn regulates valve 36. Whensensor 37 outputs a signal indicating that gas is present in gascollection plenum, controller 33 opens valve 36, thereby coupling gascollection plenum 50 to suction source 34, such as a vacuum bottle, pumpor standard operating room suction port, to evacuate the gas. Once thegas is evacuated, and the sensor detects blood at an appropriate levelin gas collection plenum 50, the sensor changes its output.Correspondingly, controller 33 then closes valve 36. In this manner, gasis continuously monitored and then automatically removed from the bloodby blood handling system 30.

[0057] Referring now to FIG. 4, additional features of the presentinvention are described. FIG. 4 is a cross-sectional view of apparatussimilar to that of FIG. 3, but in addition includes one or more reliefareas 80 that extend radially inward from blood oxygenation element 70.Relief areas 80 preferably are disposed at a radially inward portion ofthe blood oxygenation element 70 opposite blood inlet manifold 48 andblood outlet manifold 47. Relief areas 80 permit the annular fiberbundle to expand into the relief areas during operation, whereas theannular fiber bundle 70 occupies the position indicated by dotted lines81 prior to operation.

[0058] In addition, in accordance with the progressive filtration aspectof the present invention, filter material 85 may be disposed between theannular fiber bundle and the entrance to blood outlet manifold 47.Filter element 85 provides an additional third stage of filtration forblood passing through blood processing component 31, and preferablycomprises a screen-like material having the same or smaller effectivepore size than the filter material included in gas removal/blood filter56. Because blood has already passed through two stages of filtrationbefore reaching filter element 85 (i.e., gas removal/blood filter 56 andthe fibers of blood oxygenation element 70), it is expected that thisfilter will be capable of sustaining extended use without clogging.

[0059] In operation, deoxygenated blood from patient P is routed throughone or more lines 14-16 to blood inlet 41 of blood processing component31. Blood entering gas collection plenum 50 is induced to circulatearound the exterior of gas removal/blood filter 56 until air or othergases entrapped in the blood separate out of the blood and collect inthe upper portion of the gas collection plenum. Responsive to thedetection of the presence of a predetermined level or volume of gas bysensor 37, controller 33 controls operation of valve 36 to evacuate thegas.

[0060] Applicant has observed in prototype designs that the gas removalsystem of the present invention is capable of removing large amounts ofair from the extracorporeal blood circuit during initial startup,thereby greatly reducing the amount of saline or donor blood required toprime the system. Advantageously, this feature facilitates rapid andeasy set-up of the blood handling system, as well as reduces the amountof saline or donor blood delivered to the patient.

[0061] As blood circulates around gas removal/blood filter 56 in centralvoid 51, it is drawn by the negative pressure head created by impeller75 through filter material 59 and down through central void 51 into pumpspace 55. Rotation of impeller 75 caused by drive unit 32, under thecontrol of controller 33, propels blood up curved ramp 79 into bloodinlet manifold 48.

[0062] From blood inlet manifold 48, the blood traverses bloodoxygenation element 70 where it exchanges carbon dioxide and other gasesfor oxygen. Oxygenated blood then passes through filter element 85, ifpresent (see FIG. 4), and into blood outlet manifold 47. Oxygenatedblood then is directed back to the patient through arterial line 12, oroptionally, a portion of the oxygenated blood may be recirculatedthrough line 22.

[0063] While blood handling system 30 of the present invention thus isused in substantially the same manner as previously known blood handlingequipment, it does provide a number of advantages over previously knownblood handing equipment. First, the system is simple to use, withintegrated blood processing component 31 embodying a number of bloodhandling features. Thus, for example, the clinician is not required toconnect together a pump, oxygenator, or blood filter, thereby savingtime, space and priming volume.

[0064] Blood processing component 31 advantageously may serve as aprogressive, distributed, blood filter that provides staged filtrationof the blood flow. Specifically, gas removal/blood filter 56 serves as afirst filter stage to filter out matter having a size of 40-250 microns,the fibers of blood oxygenation element 70 serve as a second filterstage to filter out particulate matter having a size of approximately100 microns and larger, and filter element 85, if present at theentrance to the blood outlet manifold 47, provides a third filter stagethat filters out material having a size of 40 microns or larger.

[0065] Another advantage of the system of the present invention is thatthe gas removal system facilitates priming of the system withsignificantly less saline or donor blood. As is conventional, beforeinitiating bypass support, the entire system must be primed with bloodto purge all air out of the system. When priming the system of thepresent invention, however, the patient's own blood pressure may be usedto fill venous lines 11, 14-16 and blood processing component 31.Advantageously, the gas removal system may be used to actively removeair and draw blood into the blood processing component.

[0066] In particular, when the gas removal system is turned on, sensor37 will detect gas in the gas collection plenum 50 and will thenactively remove the gas as described hereinabove. In this manner,extracorporeal circuit 10 can be primed by operation of the gas removalsystem. Once blood processing component 31 has been thus primed, driveunit 32 may be activated, so that impeller 75 also may be operatedtogether with the gas removal system to purge air from the circuit.Blood may be recirculated through line 22 and valve 23 until all air hasbeen purged from the system.

[0067] Yet another advantage of the system of the present invention isthat additional blood processing elements 21 may be added to the systemduring operation, with the gas removal system priming the newly addeddevice during operation. When such an element 21 is added to the systemduring operation, line 16 is temporarily clamped to isolate the locationfor new element 21. Blood processing element 21 then is connected,unprimed, in line 16. The clamps then are opened, so that any air in newelement 21 is removed automatically by the gas removal system. The gasremoval system of the present invention therefore may be used to removeair while delivering blood to the patient or when simply circulating theblood through line 22 until it is confirmed that all air from newelement 21 has been removed.

[0068] Referring now to FIG. 7, gas removal element 90 constructed foruse in a stand-alone gas removal system in accordance with the presentinvention is described. Gas removal element 90 is intended for use withpreviously known extracorporeal bypass systems to provide some of theadvantages described hereinabove.

[0069] Gas removal element 90 includes transparent housing 91 havingblood inlet 92, blood outlet 93, gas removal port 94, and sensor 95.Housing 91 encloses gas removal/blood filter 96, which in turn comprisesgenerally conical upper wall 97, support structure 98 and filtermaterial 99. Upper wall 97, support structure 98 and filter material 99may be constructed as described with respect to the embodiments of FIGS.5 or 6 set forth hereinabove. When used in conjunction with a suctionsource and suitable controller, gas removal element may be used toremove air or other gases entrained in the blood in the venous line, aswell as to facilitate priming.

[0070] Referring to FIG. 8, an alternative embodiment of the bloodprocessing component of the present invention is described. In FIG. 8,like components of the embodiment of FIG. 3 are indicated by referencenumerals increased by 100. Thus, blood processing component 100comprises housing 140 having sensor 137, blood inlet 141, blood outlet142, recirculation outlet 143, gas inlet port 144, gas outlet port 145,gas removal port 146, blood outlet manifold 147, blood inlet manifold148, gas collection plenum 150, central void 151, upper gas plenum 152,annular fiber bundle compartment 153, lower gas plenum 154 and pumpspace 155. Gas removal/blood filter 156 is disposed in gas collectionplenum 150, blood oxygenation element 170 is disposed in annular fiberbundle compartment 153, and impeller 175 is rotatably fixed in pumpspace 155.

[0071] Blood processing component 100 differs from the embodiment ofFIG. 3 in that: (1) gas removal/blood filter 156 is positioned entirelyin gas collection plenum 150 and does not extend into central void 151;(2) blood oxygenation element 170 is shorter and wider than bloodoxygenation element 70; and (3) heat exchanger 180 is disposed on bloodinlet manifold 148.

[0072] Heat exchanger 180 includes inlet port 181 and outlet port 182,and enables heated or cooled liquid, such as water, to contact the bloodinlet manifold and thereby heat or cool the blood flowing therethrough.Heat exchanger 180 also may have tubes, fins or the like to enhance heattransfer, and may be positioned at any other suitable location, such asadjacent to impeller 175. Alternatively, heat exchanger 180 may use anyother suitable heat exchange structure, such as a resistive heaterelement disposed within pump space 155.

[0073] In addition, in the embodiment of FIG. 8, gas removal/bloodfilter 156 comprises a pleated structure, rather a screen-like filtermaterial. Operation of blood processing component 100 is as describedabove with respect to the embodiment of FIG. 3, except that in additionthe blood temperature may be altered as desired for a particularapplication.

[0074] Referring now to FIGS. 9 and 10, further details of thecentrifugal pump employed in the blood processing component of thepresent invention are described. Centrifugal pump 200 includes impeller201 having a plurality of arcuate vanes 202 integrally formed with disk203. Shaft 204 includes lower portion 205 that is press fit or adhesivebonded into the bottom of housing 40 (see FIG. 3), and upper portion 206that accepts seal 207, bearings 208 and sleeve 209. Sleeve 209 is pressfit or adhesive bonded to the interior of a bore in hub 210 of impeller201. Seal 207 prevents blood from entering bearings 207.

[0075] As shown in FIG. 10, impeller 201 preferably comprises aninjection moldable plastic, such as polycarbonate, and is case in twosections. A first section includes lower portion 211 of disk 203 and hub210, and includes a recess that accepts a ferromagnetic washer 212. Inaccordance with another aspect of the present invention, washer 212includes through holes 213, which permit the injection process to becompleted. Holes 213 also serve to define magnetic poles in the washer,that permit the impeller to become magnetically coupled to permanentmagnets, or electromagnets, employed in drive unit 32.

[0076] During a second step of the injection molding process, firstsection 211 is placed in a suitable mold, and the remainder of impeller201 (illustratively shown at 214) is formed by injecting material intothe mold through holes 213 in the first section and washer 212. Whenfully molded, washer 212 is completely encased in the plastic, toprevent undesirable blood-metal interaction.

[0077]FIGS. 11A and 11B depict an illustrative embodiment of the bloodhandling system of the present invention. In this embodiment, from whichall blood, gas and electrical lines have been omitted for clarity,microprocessor-driven controller 33 (see FIG. 1) and a back-up batteryare enclosed in wheeled base 220. Pole 221 is mounted in base 220, andincludes support arm 222 that supports blood processing component 31 ondrive unit 32. Support arm 222 also carries solenoid 223 that controlsvalve 36, which is in turn coupled to a suction source, such as thehospital wall suction port found in most operating rooms. Pole 221 alsocarries support arm 224, which carries display screen 225. Screen 225preferably is a touch-sensitive screen coupled to the controller, andserves as both an input device for the blood handling system and adisplay of system function.

[0078]FIGS. 12A and 12B provide representative samples of theinformation displayed on the main windows of the blood handling system.As will of course be understood by one of ordinary skill in the art ofcomputer-controlled equipment, the software used to program operation ofthe controller may include a number of set-up screens to adjustparticular system parameters. FIGS. 12A and 12B are therefore thewindows that will most commonly be displayed by the clinician during aprocedure.

[0079] The display of FIG. 12A, includes an indicator of battery status,a series of timers for pump operation, duration of cross-clamping, andan auxiliary timer, arterial and venous temperatures and pressures, asmeasured, for example, at the blood inlet and blood outlet of the bloodprocessing component, the speed of the centrifugal pump and thecorresponding blood flow rate. Preferably, the controller is programmedwith a number of algorithms for determining an appropriate blood flowrate during the procedure, as determined based on body surface area(BSA). The window also may display the value of BSA determined by theselected algorithm based on the patient's dimensions, and the suggestedblood flow rate.

[0080] The display of FIG. 12B includes much of the same informationprovided in the window of FIG. 12A, but in addition may displaytemperatures and pressures graphically as well as numerically, so thatthe clinician can quickly identify trends in the data and takeappropriate corrective measures. In addition, a lower portion of thewindows displayed in FIGS. 12A and 12B may present system status or helpmessages, and include touch sensitive buttons that permit to access theother available functions.

[0081] Although preferred illustrative embodiments of the presentinvention are described above, it will be evident to one skilled in theart that various changes and modifications may be made without departingfrom the invention. It is intended in the appended claims to cover allsuch changes and modifications that fall within the true spirit andscope of the invention.

What is claimed is:
 1. Apparatus for oxygenating and pumping bloodcomprising: a housing; a gas removal system coupled to the housing; ablood oxygenation element disposed within the housing; and a pumpcoupled in fluid communication with the blood oxygenation element. 2.The apparatus of claim 1 wherein the gas removal system comprises: asensor that detects the presence of gas within the housing and outputs asignal; and a controller that controls operation of the apparatusresponsive to the signal.
 3. The apparatus of claim 2 wherein the gasremoval system further comprises: a line adapted to be coupled to asuction source; and a valve coupled to the line between the housing andthe suction source, wherein the valve is operated responsive to thecontroller.
 4. The apparatus of claim 1 wherein the blood oxygenationelement comprises an annular fiber bundle.
 5. The apparatus of claim 4wherein the housing includes a central void and the annular fiber bundleis disposed surrounding the central void.
 6. The apparatus of claim 5wherein the gas removal system further comprises a filter elementdisposed at least partially in the central void.
 7. The apparatus ofclaim 6 wherein the filter element further comprises at least onebaffle.
 8. The apparatus of claim 5 wherein the gas removal systemfurther comprises a filter element disposed at an inlet to the centralvoid, the filter element comprising a pleated material.
 9. The apparatusof claim 1 wherein the housing includes a blood inlet manifold and ablood outlet manifold, and the blood inlet manifold is disposed on adiametrically opposite side of the housing from the blood outletmanifold.
 10. The apparatus of claim 9 wherein the pump is disposedwithin the housing.
 11. The apparatus of claim 1, further comprising aheat exchanger mounted to the housing.
 12. Apparatus for oxygenating andpumping blood comprising: a housing; a blood oxygenation element havingan annular fiber bundle disposed within the housing surrounding acentral void, the blood oxygenation element having an inlet and anoutlet, the inlet being disposed on a diametrically opposite side of theannular fiber bundle from the outlet; and a pump coupled in fluidcommunication with the blood oxygenation element, the pump having a pumpinlet and a pump outlet coupled to the inlet.
 13. The apparatus of claim12 wherein the housing includes an inlet manifold and an outletmanifold, the inlet manifold extending along a first side of the housingand the outlet manifold extending along a diametrically opposite side ofthe housing.
 14. The apparatus of claim 13 wherein the housing furtherincludes a relief area on an interior wall of the housing opposite to atleast one of the inlet manifold and the outlet manifold.
 15. Theapparatus of claim 12 wherein the pump is mounted within the housingbelow the blood oxygenation element.
 16. The apparatus of claim 12,further comprising a gas removal system.
 17. The apparatus of claim 16wherein the gas removal system comprises: a sensor that detects thepresence of gas within the housing and outputs a signal; and acontroller that controls operation of the apparatus responsive to thesignal.
 18. The apparatus of claim 17 wherein the gas removal systemfurther comprises: a line adapted to be coupled to a suction source; anda valve coupled to the line between the housing and the suction source,wherein the valve is operated responsive to the controller.
 19. Theapparatus of claim 16 wherein the gas removal system further comprises afilter element disposed at least partially in the central void.
 20. Theapparatus of claim 16 wherein the filter element further comprises atleast one baffle.
 21. The apparatus of claim 16 wherein the gas removalsystem further comprises a filter element disposed at an inlet to thecentral void, the filter element comprising a pleated material.
 22. Agas removal system for removing air from blood, comprising: a housinghaving an interior, a blood inlet and a blood outlet; a sensorpositioned to sense gas within the interior of the housing; and a filterelement disposed within the interior of the housing.
 23. The gas removalsystem of claim 22 wherein the filter element is substantiallycylindrical
 24. The gas removal system of claim 23 wherein the filterelement comprises a pleated material.
 25. The gas removal system ofclaim 22, wherein the sensor uses a sensing technique selected from thegroup consisting of: detection by capacitance, direct resistance, lightabsorbance, light refractance, and ultrasonic energy transmittance. 26.The gas removal system of claim 22, further comprising a valve operablycoupled to the sensor, the valve opening responsive to detection of gasby the sensor.
 27. The gas removal system of claim 22, furthercomprising at least one baffle disposed within the filter element. 28.Apparatus for removing gas from a blood flow, comprising: a housinghaving an interior; an inlet leading to the interior; an outlet coupledto the interior for removing blood from the interior; a filter elementdisposed within the housing and positioned to separate the inlet fromoutlet so that blood entering the inlet must pass through the filterelement; and a sensor coupled to the housing, the sensor determiningwhether gas is present.
 29. The apparatus of claim 28 wherein the inletdirects the blood in a substantially tangential direction so that bloodinitially circulates within the interior.
 30. The apparatus of claim 28wherein the sensor is operably coupled to a valve, the valve openingwhen the sensor determines that gas is present.
 31. The apparatus ofclaim 28 wherein the valve is adapted to be coupled to a source ofsuction.
 32. A method of priming a blood handling system, comprising thesteps of: providing a gas removal system, a blood oxygenation elementand a pump, the gas removal device having a sensor that detects whetherthe presence of gas, the sensor operably coupled to a valve that openswhen gas is detected by the sensor to permit removal of the gas;coupling the gas removal device, blood oxygenation element and pump toan arterial cannulae and a venous cannulae; and priming the system withblood or saline to remove air from the system by activating the gasremoval system.
 33. The method of claim 31 wherein the providing step iscarried out with the gas removal device being mounted to a commonhousing with at least one of the pump and the blood oxygenation element.34. The method of claim 33 wherein the providing step is carried outwith the gas removal device being mounted a housing that encloses thepump and the blood oxygenation element.